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arXiv 2410.02676astro-ph.CO
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原初磁场诱导的物质功率谱:从线性到非线性区域

Matter power spectrum induced by primordial magnetic fields: from the linear to the non-linear regime

SISSA - International School for Advanced Studies(国际高等研究院);INFN – National Institute for Nuclear Physics(意大利国家核物理研究所);IFPU, Institute for Fundamental Physics of the Universe(宇宙基础物理研究所);ICSC - Italian Research Center on High Performance Computing, Big Data and Quantum Computing(意大利高性能计算、大数据和量子计算研究中心)

Pranjal Ralegankar, Enrico Garaldi, Matteo Viel

AI总结:

本研究通过首次磁流体动力学模拟,揭示原初磁场诱导的物质功率谱在非线性区域饱和而非被抑制,并纠正了以往研究在转变处的高估,为精确约束原初磁场提供了新依据。

摘要:

线性理论预言原初磁场(PMFs)在小尺度上增强物质功率谱。然而,线性近似在足够小的尺度上失效,此时PMF诱导的重子扰动会反作用于磁场。以往研究基于磁金斯尺度的论证,假设重子功率谱在该非线性区域会被急剧抑制。我们首次开展专门的磁流体动力学(MHD)模拟,以研究从线性到非线性区域的转变。我们的模拟证实了大尺度上的预期线性行为。然而,在非线性区域,我们发现无量纲重子功率谱饱和至一个$\mathcal{O}(1)$的值,这与先前的解析预期形成对比。此外,我们的结果表明,过去多项研究在接近非线性转变处将总物质功率谱高估了数个数量级。因此,本工作所呈现的结果有助于从结构形成过程和/或宇宙结构的不同示踪体中获得对PMFs更精确的约束。

英文摘要:

Linear theory predicts that primordial magnetic fields (PMFs) enhance the matter power spectrum on small scales. However, the linear approximation breaks down on sufficiently small scales where PMF-induced baryon perturbations back-react onto the magnetic fields. Previous studies assumed that the baryon power spectrum would be sharply suppressed in this non-linear regime, based on arguments related to the magnetic Jeans scale. For the first time, we perform dedicated magnetohydrodynamic (MHD) simulations to investigate the transition from the linear to the non-linear regime. Our simulations confirm the expected linear behavior on large scales. In the non-linear regime, however, we find that the dimensionless baryon power spectrum saturates to an $\mathcal{O}(1)$ value, which contrasts with previous analytical expectations. Additionally, our results show that several past studies overestimated the total matter power spectrum by orders of magnitude near the transition to non-linearity. Thus, the results presented in this work are useful to obtain more accurate constraints on PMFs from structure formation processes and/or different tracers of cosmic structures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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